Retract erroneous go module versions (#11)

From the brief stint of the PGV repository being renamed to
`protovalidate`, the Go module proxy has become a bit confused about
this module. We should be able to correct the proxy (and potentially
pkg.go.dev documentation) by creating the module directly and retracting
all previous versions reported here:

```sh
$ curl https://proxy.golang.org/github.com/bufbuild/protovalidate/@v/list
# all the versions retracted in this go.mod patch
```

The current version reported by the proxy is v0.1.5, so this should work
according to the retract documentation.

```sh
$ curl https://proxy.golang.org/github.com/bufbuild/protovalidate/@latest 
{"Version":"v0.1.5","Time":"2023-06-01T18:26:24Z","Origin":{"VCS":"git","URL":"https://github.com/bufbuild/protovalidate","Ref":"refs/tags/v0.1.5","Hash":"9c8e723aa8d7d34c72701585e3da2323203d4e85"}}%                              
```

go.mod

@@ -0,0 +1,61 @@
+module github.com/bufbuild/protovalidate
+
+go 1.20
+
+// invalid versions accidentally inherited from PGV
+retract (
+	v1.0.2-SNAPSHOT.9
+	v1.0.1
+	v1.0.0
+	v0.10.1
+	v0.10.0
+	v0.9.1
+	v0.9.0
+	v0.8.0
+	v0.7.0
+	v0.6.13
+	v0.6.12
+	v0.6.9-rc.0
+	v0.6.8
+	v0.6.7
+	v0.6.7-java
+	v0.6.6
+	v0.6.5
+	v0.6.4
+	v0.6.3
+	v0.6.3-java
+	v0.6.2
+	v0.6.2-java
+	v0.6.1
+	v0.6.1-java
+	v0.6.0
+	v0.5.1
+	v0.5.0
+	v0.4.1
+	v0.4.1-java
+	v0.4.0
+	v0.4.0-java
+	v0.3.0-java
+	v0.2.0-java
+	v0.1.6
+	v0.1.5
+	v0.1.4
+	v0.1.3
+	v0.1.2
+	v0.1.1
+	v0.1.0
+	v0.0.14
+	v0.0.13
+	v0.0.12
+	v0.0.11
+	v0.0.10
+	v0.0.9
+	v0.0.8
+	v0.0.7
+	v0.0.6
+	v0.0.5
+	v0.0.4
+	v0.0.3
+	v0.0.2
+	v0.0.1
+)

go.work

@@ -1,3 +1,6 @@
 go 1.18
 
-use ./tools
+use (
+	./tools
+	.
+)